This application claims priority of Japanese patent Application No. 2000-177180, filed on Jun. 8, 2000.
1. Field of the Invention
The present invention relates to a speaker structure.
2. Description of the Related Art
FIG. 7 is a section view of a prior art speaker structure. In FIG. 7, the reference numeral 100 denotes a box-style cabinet which is equipped with a speaker 200. The speaker 200 comprises a cone 201, a frame 202, a voice coil 203, a magnetic circuit 204, etc. The magnetic circuit 204 comprises a plate 205, a magnet 206, a yoke 207, etc. The speaker 200 is fixed at the front face of the cabinet 100 with screws 101.
In this prior art structure, vibration of the speaker is easily transmitted to the cabinet, and thereby an out-of-phase sound is generated by the cabinet. This is a cause of muddiness of the sound which is output from the speaker structure. In addition, when a sound is generated at the cone 201, reaction to the movement of the cone 201 arises on the yoke 207. Since the yoke 207 is apt to vibrate, the efficiency of energy transmission from the corn to air is low. This causes a bad transient characteristic of the sound (feeling of the sound speed) which is output from the speaker structure.
In order to solve such problems, speaker structures wherein a speaker is fixed at the front face of a cabinet, and a yoke of the speaker is supported directly by a supporting rod of the speaker structure, have been proposed in the patent applications of publications (Kokai) No. 11-146471 and No. 5-153680. However, due to low structural strength of these speaker structures, there has been such a problem that the speaker structure mounted in a car is broken due to the vibration of the car in motion. Increasing the strength of the speaker structure brings new problems such as increasing its weight and making its structure more complex.
It is an object of the present invention to provide a speaker structure with a simple configuration while maintaining good sound quality to solve the problems stated above.
In order to achieve the above object, the speaker structure comprises a first vibration plate, a first frame for fixing the perimeter of the first vibration plate, a first speaker having a first magnetic circuit for converting a signal to the vibration of the first vibration plate, a second vibration plate, a second frame for fixing the perimeter of the second vibration plate, and a second speaker having a second magnetic circuit for converting a signal to the vibration of the second vibration plate, and a fixing unit for fixing the first magnetic circuit and the second magnetic circuit at their backs.
In addition, it is preferable that the speaker structure has a means for supplying the same signals in phase to the first and the second magnetic circuits.
It is also preferable that the speaker structure has a cabinet for covering the first and second speakers, a supporting means for supporting the fixing unit, a shock absorber placed between the first frame and the cabinet, a shock absorber placed between the second frame and the cabinet, and a shock absorber placed between the supporting means and the cabinet, and thereby the cabinet is kept in floating state compared to the first and second speakers and the supporting means.
It is also preferable that the speaker structure has guides to be engaged with the edges of the cabinet, provided on the backs of the first and second frames.
It is also preferable that the speaker structure has a door unit provided on the cabinet.
It is also preferable that the fixing unit has a first rib fixed at the first magnetic circuit, a second rib fixed at the second magnetic circuit, and a connecting unit for connecting the first and the second ribs.
It is also preferable that the speaker structure has a intermediate supporter which is fixed at the fixing unit and has contact with the inner surface of the cabinet, and it is also preferable that the intermediate supporter is in contact with the inner surface of the cabinet via a shock absorber, and that a sound absorber is mounted on the intermediate supporter.
It is also preferable that the cabinet has an opening for air discharging.